A wide variety of disposable absorbent articles are designed not only to be efficient in the absorption of body fluids such as urine, blood, menses and the like, but also to be sanitary and comfortable in-use, are known in literature. Disposable absorbent products of this type generally comprise a fluid-permeable topsheet material, an absorbent core (or a fluid storage layer), and a fluid-impermeable backsheet material. Various shapes, sizes and thicknesses of such articles have been explored in an attempt to make their use more comfortable and convenient.
For some time now, studies for such disposable absorbent articles have been primarily focused on the absorptive capacity of the article. As a result, various absorbent polymers with high absorptive power have been developed. Such known superabsorbent materials (also known as hydrogel-forming absorbent polymers) are capable of absorbing from about 30 to 60 grams of water per gram of polymer.
More recently, research has been focused on the removal of foul odors and the prevention of skin diseases such as dermatitis, rash and redness caused by wearing a disposable absorbent article for a relatively long time. Many body fluids have an unpleasant odor (or an malodor), or develop such an odor when in contact with air and/or bacteria for prolonged periods. Additionally, urine and/or other exudates absorbed into the absorbent article are converted to ammonia by urease produced by skin-flora, i.e., a group of normal microorganisms on the skin. This ammonia, in turn, may cause dermatitis, rash and/or other forms of skin irritation. Such disease of the skin in infants can be a serious medical matter which, in extreme cases, can result in death.
Antimicrobial materials and bactericides in general are chemical compositions that are used to prevent microbiological contamination and deterioration of products, materials, and systems. Such antimicrobial materials and bactericides can also effectively work for the removal or reduction of foul odors developed from disposable absorbent articles which has already absorbed body fluids. However, depending on the manner of the application of antimicrobial materials or bactericides in disposable absorbent articles, it is found that such antimicrobial materials and bactericides tend to affect the absorptive capacity of disposable absorbent articles.
For example, Japanese Patent (Kokoku) Publication No. H4-17058 discloses a disposable diaper which includes an absorbent layer containing a superabsorbent material and a antimicrobial material included in the superabsorbent material. Similarly, Japanese Patent (Kokai) Publication No. H5-277143 discloses a disposable diaper which includes a superabsorbent material containing an odor reduction material. Metalphthalocyanine derivatives are disclosed in H5-277143 as examples of the odor reduction material. Further, Japanese Patent (Kokai) Publication No. S64-25856 discloses a sanitary napkin which includes an absorbent sheet including a superabsorbent material and a metalphthalocyanine derivative as an odor reduction material. In those structures disclosed, the antimicrobial or odor reduction material is in contact with the superabsorbent material, as a result, the absorptive capacity of the superabsorbent material tends to be decreased because of the existence of the antimicrobial or odor reduction material.
Based on the foregoing, there is a need for disposable absorbent articles whose absorptive capacity is not affected by the use of a metalphthalocyanine or its derivatives as an odor reduction material.